Several spinal fixation systems exist for stabilizing the spine so that bony fusion is achieved. The majority of these fixation systems use either plates or rods that attach to screws inserted into the vertebral body or the pedicles. Plate fixation systems are more commonly used in the anterior part of the spine, i.e., vertebral bodies, while rods are the accepted standard for posterior fixation. These spine fixation systems can be extended along the sides of the spine by connecting two adjacent pedicles at a time similar to the concept of a bicycle chain.
Single or multilevel segmental posterior fusions are most commonly achieved by contouring a solid ¼-inch cylindrical rod and attaching it to adjacent pedicle screws on each side of the spine using various connecting assemblies. This longitudinal construction can be made more rigid by connecting the rods to each other with a cross-connector (or translateral linking assembly) to form an “H” configuration.
The rod system requires contouring of each rod across several vertebras in many cases. The contouring of each rod depends on the configuration of the pedicle screws and varies from side to side in the same patient and among patients. This may add considerable time to an operation. Recent generations of pedicle screws and rod cross-connectors seek to diminish this drawback by allowing variable axes of movements in the pedicle screw recess for the rod or in the rod connectors. However, in most cases this adds another level of complexity to the operation and often further increases the operative time. This increase in operative time and the complexity of the cross-connectors put substantial stress on the surgeon and the supporting staff. Accordingly, cross-connectors that reduce the complexity level of the spinal stabilization assemblies are desirable.